Recalls linked to possibly listeria-tainted sunflower seeds processed in Minnesota have mushroomed, and now involve several major food companies across the nation.

The recalls connected to the SunOpta plant in Crookston include items sold in 28 states by Kroger, one of the nation’s largest supermarket operators, as well as dozens of products made by TreeHouse Foods, a major private-label food manufacturer.

Also, Pittsburgh-based Giant Eagle, a regional supermarket operator, has recalled bulk sunflower seeds sold at its Market District stores in Pittsburgh and in central and northeast Ohio.

And California-based Ghiringhelli Specialty Foods recalled 33,610 pounds of broccoli and kale salad sold through Trader Joe’s stores in Arizona, California, Nevada and Utah.

All of the companies said their recalls stemmed from sunflower seeds supplied to them by SunOpta, a Toronto-based company with a major presence in Minnesota.

While listeria can cause a potentially fatal infection, there have been no reports of illnesses from any of the sunflower seed products recalled this week.

SunOpta itself Wednesday announced a “limited” recall of bagged sunflower seeds sold under the popular Planters brand (which is owned by Kraft Heinz), as well as the Dakota’s Best Biggy’z label. Those products were packaged by SunOpta, while the other recalls involve sunflower seeds supplied by SunOpta.

SunOpta, which specializes in non-GMO and organic ingredients and products, has its U.S. headquarters in Edina and owns several plants in Minnesota, where it employs about 550 people. The Crookston plant linked to the listeria recalls has been shut down since April 21.

Listeria monocytogenes bacteria can cause listeriosis, a potentially deadly infection. It strikes hard at pregnant women, newborns, older adults and people with weakened immune systems, according to the Centers for Disease Control. About 1,600 illnesses and 260 deaths are caused annually by listeriosis in the U.S.

Cincinnati-based Kroger recalled its store-branded sunflower kernels, sunflower salad toppers and cranberry trail mix. The recall is spread across 11 of Kroger’s chains in states across the country, though not in Minnesota where Kroger has little presence. “It affects a majority of our businesses,” said Keith Dailey, a Kroger spokesman.

TreeHouse Foods, based in suburban Chicago, recalled dozens of products under about 100 different UPC codes, all of them containing sunflower seeds, and many of them snack bars. Some of the recalled TreeHouse products were sold through major grocery chains Meijer and Hy-Vee, the latter of which operates in Minnesota.

A TreeHouse executive told stock analysts on an earnings conference call Thursday that “less than 100,000 cases” of products were affected by the recall.

SunOpta supplies packaged food companies with natural ingredients from soybeans to fruit, and it also makes finished products — soymilk and orange juice, for instance — for major food retailers. Sunflower seeds and nuts are a significant business for SunOpta, and North Dakota and South Dakota are by far the nation’s two largest sunflower producing states, followed by Minnesota.

A SunOpta spokesman said Wednesday that the company discovered the listeria problem after a call from one of its corporate customers. The customer tested a batch of sunflower seeds that came up positive for listeria.

Sunflower seed production includes a “kill step” to zap listeria, but the contamination appears to have occurred after that point, the company has said.